Our research focuses on understanding how sensory signals are processed by the nervous system. A key element of this endeavor is to understand how neural codes package the sensory information efficiently. Some would describe this task as "cracking the neural code". Using gymnotiform weakly electric fish as a model system we concentrate on characterizing how communication signals are encoded in the sensory system. To guide behavior, the relevant information present in these signals must be extracted and transmitted to higher brain areas. From the receptors, to the primary sensory area in the hindbrain (ELL) to midbrain and forebrain, the transformations that the signal undergoes in each neural population must be understood.
The ELL has been the focus of our research so far. We use a combination of in vivo electrophysiology, computational neuroscience tools, behavioral assays, histology, imaging, pharmacological manipulations and comparative studies. We characterized the way ELL neurons encode communication signals. We revealed how cellular and network dynamics influence the transformation operated by the system. We demonstrated how the coding scheme and the transformation implemented by the system are tailored to the behavioral aptitudes of the fish. We are examining how spatial information and localization of a social partner is shaped by the network and population dynamics of sensory neurons. The research in our lab is at the intersection of three connected areas of neuroscience: Systems Neuroscience, Computational Neuroscience and Neuroethology. For this reason, we find it very important to relate neural activity with behavior, to characterize mathematically the process implemented by the neural network, and identify the cellular and network mechanisms that dictate how signals are processed.
Four main research foci occupy our lab members these days:
-Using a comparative approach to study the neural encoding of chirps, paired with behavioral assessment of their perceptual capacity, to understand how neural codes, communication signals and behaviors co-evolved (e.g. Allen & Marsat, 2018; Allen & Marsat, 2019; click on these links for the pdf).
-Understanding how specific neural properties like bursting or neural heterogeneity is shaped and specialized for specific tasks (e.g. Ly & Marsat, 2018; Motipally et al, 2019; click on these links for the pdf).
-Starting to understand how the spatial aspect of communication signals is encoded, how space is represented in the sensory system, and how the spatial dynamics of stimuli influence sensory responses (e.g. Milam, Ramachandra & Marsat, 2019; click on this link for the pdf).
-Improve the computational and analytical methods used to study neural coding and neural processing. This includes decoding models, spike train analysis, machine learning, ect ... (e.g. Marsat et al. 2021; click this link to the pre-press article).
For another general overview see this news article in Research Features: